In modern military vehicles, it is often desirable to have several electrical circuits within the vehicle, each circuit having a different operating voltage. One approach to servicing such a group of circuits is to have a plurality of batteries in series and to have each electrical circuit draw power only from some of these batteries so as to receive the desired voltage for that circuit. One problem with this approach is that batteries servicing both higher and lower voltage circuits are more heavily drained and fail sooner than the other batteries.
In many electrical utility circuits for military or other vehicles, there are a number of electrical components that are energized or de-energized independently of one another. Therefore the number of components drawing power from the battery and the total power demanded by the circuit will vary. A common example of such a circuit would be a light circuit having turn signal lights, head lights, brake lights and back up lights. To prolong life of the electrical components and to prevent power fluctuations from affecting such components as gauges, it is desirable for a power supply to maintain a steady voltage level to any given energized component. The steady voltage level must be maintained no matter what other components in the circuit are energized or de-energized.